This invention relates to apparatus for taking a workpiece from a procession of workpieces and locating it at a tool, and more particularly, but not exclusively, to apparatus for removing a cup from a chute to a locating means in a press tool comprising a punch and die.
European Patent 0049923 B1 describes apparatus in which a procession of cups fall down a chute from which the leading cup is removed by a generally radial portion of a spiral cam disc. The spiral cam disc drives each cup along an arcuate guide rail which extends to a tangential guide rail portion. This tangential guide rail portion leads to a stop member which holds the cup in the desired location while the cam rotates to collect another cup. The spiral portion of the cam surface serves continuously to control descent of each cup from the chute but, recognising that a complete spiral periphery would leave a cup at the stop member free to bounce or spring out of correct location, the cam profile has an arcuate portion between the generally radial portion and spiral. This arcuate portion serves to provide a temporary holding force on a cup at the stop member. However, the presence of this arcuate portion of cam profile reduces the extent of the spiral portion of the cam profile and so introduces problems:
(i) the rate of descent of cups from the chute is temporarily stopped by the arcuate portion so that inertia forces develop in the intermittently advancing cups; PA1 (ii) the peripheral extent of arcuate portion and speed of rotation of the cam disc limit the period of holding available; and PA1 (iii) as improved presses are developed to run at higher speeds of about 350 strokes per minute we have found that an improvement in the delivery and holding at the stop member is required. PA1 a feed chute for feeding a procession of workpieces; PA1 a rotatable feed cam adjacent the chute and having a cam profile which includes a spiral portion around the axis of rotation of the cam to lower a workpiece from the chute and drive the workpiece towards the stop member; PA1 an outer guide member having a spiral curved portion which extends around the axis of rotation of the feed cam and a further guide portion extending in a direction susbtantially tangential to the curved portion; PA1 and a stationary stop member adapted to receive the workpiece from the further guide portion, characterised in that, a clamp member is operably connected to the feed cam to move from a retracted position to engage with a workpiece received from the feed cam and urge the workpiece along said further guide portion into the stationary stop member where it is clamped. PA1 (1) The article is under positive control forces at all times during transport from the chute to the stop member so that continuous motion of each article is achieved and stop/start forces are avoided. PA1 (2) Separation of the transport function of the feed cam from the prior art holding function, by provision of a separate holding means, increase the ability of our apparatus to tolerate minor variation of article shape such as cups which are not quite circular. PA1 (3) The positive control forces provided enable this apparatus to feed press tools stroking at rates in excess of 300 stokes per minute, because risk of distortion of the cup is reduced.